The objective of this research is to assess the importance of regular systems of inbreeding and various modes of reproductive compensation for the mortality and morbidity ensuring from deleterious mutations. In particular, the immediate, transition, and equilibrium genetic loads associated with introducing various mating and reproductive strategies will be contrasted. This will contribute to the theoretical foundation for breeding research strains of animals as well as preserving endangered species, and will reveal some of the ultimate consequences of social practices in man. Populations will be modelled with discrete non-overlapping generations; this will allow Markov chain models which may be analyzed directly for small populations, and branching processes (on graphs) may model larger populations. Random simulation will also be employed. Recurrent mutation will be studied for the equilibrium load, but the consequences of a single deleterious allele will often be an appropriate model for the dynamic phase before equilibrium is obtained after the mating or reproductive structure has changed. Infinite as well as finite populations will be studied.